1) Field of the Invention
This invention relates generally to material handling equipment. More particularly, the present invention relates to a hand truck which allows for loading and unloading of objects thereon such as cases of beverage cans, in a manner which substantially eliminates any necessity for the operator to bend over in order to place an object onto the hand truck or to remove an object therefrom.
2) Related Prior Art
Hand trucks for transporting objects have been in use for many years. Such hand trucks are generally comprised of a toe plate which is fixed in a perpendicular orientation to a support frame, with a set of wheels located in approximately at the connection point. The toe plate is loaded with objects, either by placing objects directly thereon or by sliding the toe plate underneath the object. The support frame is then grasped by the operator and the wheels are temporarily immobilized while the operator rotates the support frame to lift the toe plate, and the objects placed thereon, until only the wheels remain on the ground. The hand truck can then be rolled by the operator to transport the objects thereon to a desired location. When it is desired to unload the hand truck the wheels are again immobilized and the toe plate is again rotated until it rests on the ground. The operator then may remove objects from the hand truck or may remove the hand truck by removing the toe plate from beneath the objects.
It has often been desirable for certain types of lifting requirements to modify the standard hand truck to make it more useful to the operator during loading and unloading thereof. Such modifications usually include a toe plate which is movable along the support frame in such a manner that the toe plate may be adjusted to a convenient position for either loading or unloading of objects thereon. A hand truck exemplary of this design is shown in U.S. Pat. No. 3,052,323 to Hopfeld which shows a hand truck having a movable toe plate which is adjustable along the frame by means of a chain and hydraulic pump. Other hand trucks exemplary of this concept are U.S. Pat. No. 3,907,138 Rhodes, U.S. Pat. No. 3,704,799 Morris, Jr. and U.S. Pat. No. 2,598,489 Bayer et al., which show hand trucks which have been modified to allow the toe plate to adjust along the frame thereof by means of a threaded screw.
In each of the prior art devices, the toe plate must be positioned by the operator through the operators actuation of the mechanism which moves the toe plate. This can become very inconvenient when the operator must load and unload a very large number of objects. Since the operator must readjust the location of the toe plate each time an object is loaded or unloaded from the hand truck, a very large amount of time can be expended in operating a hand truck when a very large number of objects must be loaded and unloaded. An example of this inconvenience can be illustrated in the situation where a delivery person delivering objects such as cases of beverage cans or other goods, must quickly load a hand truck with several cases and move them a very short distance into a store and then quickly unload them again. In this instance, a requirement for the operator to readjust the toe plate location in between loading and/or unloading of each individual case, can easily triple or quadruple the time factor involved in moving the cases into the store.
There is therefore a need to develop a hand truck which has a moveable toe plate which can automatically move to its proper position on the frame, dependent upon the load placed thereon or removed therefrom.
Also, an operator in the example described above must often bend over many times to load cases of cans onto a hand truck, and then bend over again several times when unloading the cases. Such bending and lifting, especially when done successively hundreds of times each working day, can have serious effect on the operators health. Muscle strain, back injuries, etc. are very common for operators of this type. Such injuries may be minimized or eliminated by a hand truck having a toe plate which can be adjusted to a proper height above the ground so as to alleviate any need for an operator to bend over to load or unload objects therefrom. Such a device must also be capable of adjusting the location of the toe plate in accordance with the load located thereon, in order that the load itself is properly positioned at a height which allows further loading or unloading without the need for the operator to bend while lifting.